I'm one of the few that's seen them all (though not all of them are finished, so I haven't finished them all, which is a different question entirely). I try to watch at least a few episodes of every anime and dump the ones that don't tickle my fancy. I keep up with info about those shows in case they get my interest later on and start them back up, though.
As for favorites, counting ONLY those represented and in no particular order, I'd have to say Strike Witches, Spice and Wolf, Gundam 00, Code Geass, Clannad, ef, and Macross Frontier. There are other series that I really like, but these are the favorites of the bunch.
Looking forward to this year's Mote^2!!